A standard extruding assembly for making a strand has a nozzle formed with a passage having an upstream end connected to an extruder and a downstream end that is formed as a slot, that is with a relatively great length and a relatively short width. Typically the lengthwise dimension of the slot is measured horizontally and is defined between edges of upper and lower nozzle parts and the width is a vertical dimension. The extruder feeds a hot and liquefied thermoplastic resin to the upstream end of the passage under pressure so that it exits from the nozzle at the slot as a ribbon-like strand having a width dimension equal to the slot length and a thickness equal to the slot width. One edge of the slot can be nonstraight to impart a desired surface profile to the strand thus produced, giving a veined or marbled appearance to it for use as a panel edge, molding, or the like.
The width or height, that is the smaller crosswise dimension, of the slot can normally be varied to produce workpieces of different thicknesses. The slot length cannot, however, so that when the workpiece width must be changed, it is necessary to replace the nozzle or replace some parts of it. This is a fairly expensive procedure, requiring the manufacturer to stock a variety of different nozzles corresponding to the different workpiece widths needed.